iOS: Introduced RCTSurfaceHostingProxyRootView for migration to RCTSurfaceHostingView

Summary:
To help with migration from direct usages of RCTRootView to RCTSurfaceHostingView, RCTSurfaceHostingProxyRootView is added, which is simply a custom impl of RCTSurfaceHostingView, but will all RCTRootView APIs preserved. This makes it easy to do a drop-in replacement in native callsites:

```
// before:
RCTRootView *rootView = [[RCTRootView alloc] init...];

// after:
RCTRootView *rootView = (RCTRootView *)[[RCTSurfaceHostingProxyRootView alloc] init...];
```

Reviewed By: shergin

Differential Revision: D7141696

fbshipit-source-id: db8c447749eaa896efaa37774a9babef132128eb

React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingProxyRootView.h

@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <UIKit/UIKit.h>
+
+#import <React/RCTRootView.h>
+
+#import "RCTSurfaceHostingView.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * This is a RCTRootView-compatible implementation of RCTSurfaceHostingView.
+ * Use this class to replace all usages of RCTRootView in the app for easier migration
+ * to RCTSurfaceHostingView.
+ *
+ * WARNING: In the future, RCTRootView will be deprecated in favor of RCTSurfaceHostingView.
+ */
+@interface RCTSurfaceHostingProxyRootView : RCTSurfaceHostingView
+
+#pragma mark RCTRootView compatibility - keep these sync'ed with RCTRootView.h
+
+@property (nonatomic, copy, readonly) NSString *moduleName;
+@property (nonatomic, strong, readonly) RCTBridge *bridge;
+@property (nonatomic, copy, readwrite) NSDictionary *appProperties;
+@property (nonatomic, assign) RCTRootViewSizeFlexibility sizeFlexibility;
+@property (nonatomic, weak) id<RCTRootViewDelegate> delegate;
+@property (nonatomic, weak) UIViewController *reactViewController;
+@property (nonatomic, strong, readonly) UIView *contentView;
+@property (nonatomic, strong) UIView *loadingView;
+@property (nonatomic, assign) BOOL passThroughTouches;
+@property (nonatomic, assign) NSTimeInterval loadingViewFadeDelay;
+@property (nonatomic, assign) NSTimeInterval loadingViewFadeDuration;
+@property (nonatomic, assign) BOOL fabric;
+
+- (instancetype)initWithBridge:(RCTBridge *)bridge
+                    moduleName:(NSString *)moduleName
+             initialProperties:(NSDictionary *)initialProperties
+                        fabric:(BOOL)fabric NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)initWithBridge:(RCTBridge *)bridge
+                    moduleName:(NSString *)moduleName
+             initialProperties:(NSDictionary *)initialProperties;
+
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                       moduleName:(NSString *)moduleName
+                initialProperties:(NSDictionary *)initialProperties
+                    launchOptions:(NSDictionary *)launchOptions;
+
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                       moduleName:(NSString *)moduleName
+                initialProperties:(NSDictionary *)initialProperties
+                    launchOptions:(NSDictionary *)launchOptions
+                           fabric:(BOOL)fabric;
+
+- (void)cancelTouches;
+
+@end
+
+NS_ASSUME_NONNULL_END
+

React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingProxyRootView.mm

@@ -0,0 +1,205 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "RCTSurfaceHostingProxyRootView.h"
+
+#import <objc/runtime.h>
+
+#import "RCTAssert.h"
+#import "RCTBridge.h"
+#import "RCTLog.h"
+#import "RCTPerformanceLogger.h"
+#import "RCTProfile.h"
+#import "RCTRootContentView.h"
+#import "RCTRootViewDelegate.h"
+#import "RCTSurface.h"
+#import "UIView+React.h"
+
+static RCTSurfaceSizeMeasureMode convertToSurfaceSizeMeasureMode(RCTRootViewSizeFlexibility sizeFlexibility) {
+  switch (sizeFlexibility) {
+    case RCTRootViewSizeFlexibilityWidthAndHeight:
+      return RCTSurfaceSizeMeasureModeWidthUndefined | RCTSurfaceSizeMeasureModeHeightUndefined;
+    case RCTRootViewSizeFlexibilityWidth:
+      return RCTSurfaceSizeMeasureModeWidthUndefined | RCTSurfaceSizeMeasureModeHeightExact;
+    case RCTRootViewSizeFlexibilityHeight:
+      return RCTSurfaceSizeMeasureModeWidthExact | RCTSurfaceSizeMeasureModeHeightUndefined;
+    case RCTRootViewSizeFlexibilityNone:
+      return RCTSurfaceSizeMeasureModeWidthExact | RCTSurfaceSizeMeasureModeHeightExact;
+  }
+}
+
+static RCTRootViewSizeFlexibility convertToRootViewSizeFlexibility(RCTSurfaceSizeMeasureMode sizeMeasureMode) {
+  switch (sizeMeasureMode) {
+    case RCTSurfaceSizeMeasureModeWidthUndefined | RCTSurfaceSizeMeasureModeHeightUndefined:
+      return RCTRootViewSizeFlexibilityWidthAndHeight;
+    case RCTSurfaceSizeMeasureModeWidthUndefined | RCTSurfaceSizeMeasureModeHeightExact:
+      return RCTRootViewSizeFlexibilityWidth;
+    case RCTSurfaceSizeMeasureModeWidthExact | RCTSurfaceSizeMeasureModeHeightUndefined:
+      return RCTRootViewSizeFlexibilityHeight;
+    case RCTSurfaceSizeMeasureModeWidthExact | RCTSurfaceSizeMeasureModeHeightExact:
+    default:
+      return RCTRootViewSizeFlexibilityNone;
+  }
+}
+
+@implementation RCTSurfaceHostingProxyRootView
+
+- (instancetype)initWithBridge:(RCTBridge *)bridge
+                    moduleName:(NSString *)moduleName
+             initialProperties:(NSDictionary *)initialProperties
+                        fabric:(BOOL)fabric
+{
+  RCTAssertMainQueue();
+  RCTAssert(bridge, @"A bridge instance is required to create an RCTSurfaceHostingProxyRootView");
+  RCTAssert(moduleName, @"A moduleName is required to create an RCTSurfaceHostingProxyRootView");
+
+  RCT_PROFILE_BEGIN_EVENT(RCTProfileTagAlways, @"-[RCTSurfaceHostingProxyRootView init]", nil);
+  if (!bridge.isLoading) {
+    [bridge.performanceLogger markStartForTag:RCTPLTTI];
+  }
+
+  if (self = [super initWithBridge:bridge moduleName:moduleName initialProperties:initialProperties fabric:fabric]) {
+    self.backgroundColor = [UIColor whiteColor];
+  }
+
+  RCT_PROFILE_END_EVENT(RCTProfileTagAlways, @"");
+
+  return self;
+}
+
+- (instancetype)initWithBridge:(RCTBridge *)bridge
+                    moduleName:(NSString *)moduleName
+             initialProperties:(NSDictionary *)initialProperties
+{
+  return [self initWithBridge:bridge moduleName:moduleName initialProperties:initialProperties fabric:NO];
+}
+
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                       moduleName:(NSString *)moduleName
+                initialProperties:(NSDictionary *)initialProperties
+                    launchOptions:(NSDictionary *)launchOptions
+                           fabric:(BOOL)fabric
+{
+  RCTBridge *bridge = [[RCTBridge alloc] initWithBundleURL:bundleURL
+                                            moduleProvider:nil
+                                             launchOptions:launchOptions];
+
+  return [self initWithBridge:bridge moduleName:moduleName initialProperties:initialProperties fabric:fabric];
+}
+
+- (instancetype)initWithBundleURL:(NSURL *)bundleURL
+                       moduleName:(NSString *)moduleName
+                initialProperties:(NSDictionary *)initialProperties
+                    launchOptions:(NSDictionary *)launchOptions
+{
+  return [self initWithBundleURL:bundleURL moduleName:moduleName initialProperties:initialProperties launchOptions:launchOptions fabric:NO];
+}
+
+RCT_NOT_IMPLEMENTED(- (instancetype)initWithFrame:(CGRect)frame)
+RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:(NSCoder *)aDecoder)
+
+# pragma mark proxy methods to RCTSurfaceHostingView
+
+- (NSString *)moduleName
+{
+  return super.surface.moduleName;
+}
+
+- (RCTBridge *)bridge
+{
+  return super.surface.bridge;
+}
+
+- (BOOL)fabric
+{
+  return super.surface.fabric;
+}
+
+- (UIView *)contentView
+{
+  return self;
+}
+
+- (NSNumber *)reactTag
+{
+  return super.surface.rootViewTag;
+}
+
+- (RCTRootViewSizeFlexibility)sizeFlexibility
+{
+  return convertToRootViewSizeFlexibility(super.sizeMeasureMode);
+}
+
+- (void)setSizeFlexibility:(RCTRootViewSizeFlexibility)sizeFlexibility
+{
+  super.sizeMeasureMode = convertToSurfaceSizeMeasureMode(sizeFlexibility);
+}
+
+- (NSDictionary *)appProperties
+{
+  return super.surface.properties;
+}
+
+- (void)setAppProperties:(NSDictionary *)appProperties
+{
+  [super.surface setProperties:appProperties];
+}
+
+- (CGSize)intrinsicContentSize
+{
+  return super.surface.intrinsicSize;
+}
+
+- (UIView *)loadingView
+{
+  return super.activityIndicatorViewFactory ? super.activityIndicatorViewFactory() : nil;
+}
+
+- (void)setLoadingView:(UIView *)loadingView
+{
+  super.activityIndicatorViewFactory = ^UIView *(void) {
+    return loadingView;
+  };
+}
+
+#pragma mark RCTSurfaceDelegate proxying
+
+- (void)surface:(RCTSurface *)surface didChangeStage:(RCTSurfaceStage)stage
+{
+  [super surface:surface didChangeStage:stage];
+  if (RCTSurfaceStageIsRunning(stage)) {
+    [super.surface.bridge.performanceLogger markStopForTag:RCTPLTTI];
+    dispatch_async(dispatch_get_main_queue(), ^{
+      [[NSNotificationCenter defaultCenter] postNotificationName:RCTContentDidAppearNotification
+                                                          object:self];
+    });
+  }
+}
+
+- (void)surface:(RCTSurface *)surface didChangeIntrinsicSize:(CGSize)intrinsicSize
+{
+  [super surface:surface didChangeIntrinsicSize:intrinsicSize];
+
+  [_delegate rootViewDidChangeIntrinsicSize:(RCTRootView *)self];
+}
+
+#pragma mark legacy
+
+- (UIViewController *)reactViewController
+{
+  return _reactViewController ?: [super reactViewController];
+}
+
+#pragma mark unsupported
+
+- (void)cancelTouches
+{
+  // Not supported.
+}
+
+@end
+

React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingView.h

@@ -7,6 +7,7 @@
 
 #import <UIKit/UIKit.h>
 
+#import <React/RCTSurfaceDelegate.h>
 #import <React/RCTSurfaceSizeMeasureMode.h>
 #import <React/RCTSurfaceStage.h>
 
@@ -23,7 +24,7 @@ NS_ASSUME_NONNULL_BEGIN
  * This class can be used as easy-to-use general purpose integration point
  * of ReactNative-powered experiences in UIKit based apps.
  */
-@interface RCTSurfaceHostingView : UIView
+@interface RCTSurfaceHostingView : UIView <RCTSurfaceDelegate>
 
 /**
  * Designated initializer.
@@ -41,6 +42,15 @@ NS_ASSUME_NONNULL_BEGIN
                     moduleName:(NSString *)moduleName
              initialProperties:(NSDictionary *)initialProperties;
 
+/**
+ * Convenience initializer.
+ * To control toggle Fabric for the Surface.
+ */
+- (instancetype)initWithBridge:(RCTBridge *)bridge
+                    moduleName:(NSString *)moduleName
+             initialProperties:(NSDictionary *)initialProperties
+                        fabric:(BOOL)fabric;
+
 /**
  * Surface object which is currently using to power the view.
  * Read-only.

React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingView.mm

@@ -13,7 +13,7 @@
 #import "RCTSurfaceView.h"
 #import "RCTUtils.h"
 
-@interface RCTSurfaceHostingView () <RCTSurfaceDelegate>
+@interface RCTSurfaceHostingView ()
 
 @property (nonatomic, assign) BOOL isActivityIndicatorViewVisible;
 @property (nonatomic, assign) BOOL isSurfaceViewVisible;
@@ -33,13 +33,21 @@ RCT_NOT_IMPLEMENTED(- (nullable instancetype)initWithCoder:(NSCoder *)coder)
 - (instancetype)initWithBridge:(RCTBridge *)bridge
                     moduleName:(NSString *)moduleName
              initialProperties:(NSDictionary *)initialProperties
+                        fabric:(BOOL)fabric
 {
-  RCTSurface *surface =
-    [[RCTSurface alloc] initWithBridge:bridge
-                            moduleName:moduleName
-                     initialProperties:initialProperties];
-
+  RCTSurface *surface = [[RCTSurface alloc] initWithBridge:bridge
+                                                moduleName:moduleName
+                                         initialProperties:initialProperties
+                                                    fabric:fabric];
   return [self initWithSurface:surface];
+
+}
+
+- (instancetype)initWithBridge:(RCTBridge *)bridge
+                    moduleName:(NSString *)moduleName
+             initialProperties:(NSDictionary *)initialProperties
+{
+  return [self initWithBridge:bridge moduleName:moduleName initialProperties:initialProperties fabric:NO];
 }
 
 - (instancetype)initWithSurface:(RCTSurface *)surface